Mailx-12.x adds a lot of useful functionality to the "cmdline mail
command", which seems to be expected long years ago. Without it,
some tasks can be performed only by TUI or even GUI applications,
which makes impossible to automate things by scripts.

I am 100% in favor. I already use nail instead of mail everywhere I need
to use command line tools. What I love most is it's ability to attach files.

This looks good, but on a minimal system how many other packages
would be pulled in as dependancies over the existing mailx?

For now, "openssl" (or "nss") and "krb5-libs". Is it OK for a minimal
system?

openssl and krb5-libs are already required by openssh so I'd say it's
not a problem